N-alkyl Methacrylates Research Articles

Multiple Glass Transition and Nanophase Separation in Poly(n-alkyl methacrylate) Homopolymers

Shear data in the temperature range from −145 °C to the flow zone are presented for the poly(n-alkyl methacrylate)s from methyl (C = 1) to lauryl (C = 12). Three qualitatively different glass transitions are observed in the shear curves at 10 rad/s: (i) the conventional α process in the C < 5 members, (ii) the high temperature a process in the C > 5 members, and (iii) an additional polyethylene-like glass transition, αPE, in the C ≥ 3 members. All three processes depend systematically on side chain length. Two alternative empirical pictures for the coexistence of two glass transitions are discussed: (a) a static nanophase separation between main chains and side chains and (b) a dynamic heterogeneity with two different time and length scales.

Systematic calorimetric study of glass transition in the homologous series of poly( n-alkyl methacrylate)s: Narayanaswamy parameters in the crossover region

The glass transition in poly( n-alkyl methacrylate)s from C=1 (methyl, PMMA) over 2, 3, 4, 5, 6, 7, to C=9 (nonyl) is investigated by differential scanning calorimetry DSC, and partly by temperature modulated DSC, TMDSC. The results are compared with dielectric and heat capacity spectroscopy so far as available. The DSC thermograms are evaluated by a modified Narayanaswamy model MNM that permits a point-by-point determination of the underlying equilibrium trace of the dynamic glass transition in an Arrhenius diagram. The MNM parameters and their variations due to differently given Vogel temperatures are discussed and compared with literature values for polyvinylacetate PVAC and polystyrene PS. It seems not possible at present to determine a definite Narayanaswamy mixing parameter x for a substance as such, e.g. for PVAC and PS, the uncertainty is about Δ x=±0.2. For the homologous P nAMA series dramatic changes of x outside the Δ x uncertainty are observed near the crossover region. The results are discussed with respect to cooperativity, fragility, vitrification rate, and further characteristics of the glass transition.

Synthesis and Properties of Low-Polydispersity Poly(sulfopropylbetaine)s and Their Block Copolymers

A series of near-monodisperse sulfopropylbetaine homopolymers have been prepared by reaction of 1,3-propanesultone with poly(2-(dimethylamino)ethyl methacrylate)s produced by group-transfer polymerization. Block copolymers of 2-(dimethylamino)ethyl methacrylate and n-alkyl methacrylates gave sulfobetaine block copolymers when treated with 1,3-propanesultone. Betaine formation dramatically reduces the surface activity of both the homopolymers and the block copolymers. Chromatography and light scattering show that the betaine copolymers form polydisperse micelles on direct dissolution in water, and preliminary dissolution in a nonselective solvent (2,2,2-trifluoroethanol) is needed to give near-monodisperse micelles. Micelle aggregation numbers are controlled by the length of the hydrophobic block and are essentially independent of the hydrophilic block. The betaine homopolymers show chain expansion in aqueous NaCl solutions up to 0.1 M, due to the anti-polyelectrolyte effect. A similar effect is also obser...

Comparison of Interfacial Width of Block Copolymers of d8-Poly(methyl methacrylate) with Various Poly(n-alkyl methacrylate)s and the Respective Homopolymer Pairs as Measured by Neutron Reflection

The compatibility of d8-poly(methyl methacrylate) (d8-PMMA) and a series of poly(n-alkyl methacrylate)s (PnAlkMA) is studied by systematic variation of the length of the n-alkyl group from ethyl (E...

Ternary hydrogen-bonded polymer solutions

Ternary-phase diagrams have been experimentally determined at 100°C for systems containing a series of poly(n-alkyl methacrylates), poly(ethylene oxide) (PEO), and a solvent [4-ethyl phenol (EPh)]. A totally miscible phase diagram is experimentally determined for the poly(methyl methacrylate)/PEO/EPh system, while a closed-loop diagram is observed for the analogous system containing poly(ethyl methacrylate). The corresponding phase diagrams of analogous mixtures containing poly(n-propyl methacrylate) or poly(n-butyl methacrylate) exhibit large heterogeneous areas. Theoretically predicted phase diagrams calculated using an association model developed in our laboratory are in general accord with these observations for ternary hydrogen-bonded polymer/polymer solutions. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 1265–1271, 1998

Phase Behavior of Diblock Copolymers between Styrene and n-Alkyl Methacrylates

In contrast to most diblock copolymers which exhibit the classical upper critical ordering transition (UCOT), polystyrene-b-poly n-butyl methacrylatePS-b-PBMAhas been shown to undergo ordering upon heating through a lower critical ordering transition (LCOT). Here we report the phase behavior of a family of diblock copolymers formed from styrene and a homologous series of n-alkyl methacrylates, as determined by combined dynamic rheological testing and small-angle neutron scattering (SANS). It is shown that the shortest side chain methacrylates, with the exception of methyl methacrylate, exhibit the LCOT, while for side chains longer than n-butyl, the copolymers exhibit the classical UCOT behavior. Combined group contribution/lattice fluid model calculations of the solubility parameter and specific volume of the corresponding homopolymers qualitatively support these observations. The same calculations were further employed to molecularly design LCOT behavior into a new diblock material consisting of styrene and a random copolymer of methyl and lauryl methacrylate, denoted PS-b-P(MMA-r-LMA). The success of this approach suggests a simple semiquantitative method for predicting and designing the phase behavior of weakly interacting polymer pairs.

Structure and Dynamics of Poly(n-decyl methacrylate) below and above the Glass Transition

The structure and dynamics of the “strong” glass of poly(n-decyl methacrylate) (PnDMA) have been studied, respectively, with X-ray diffraction and dielectric spectroscopy, dynamic light scattering, and rheology at temperatures below and above the glass transition temperature Tg ∼ 215 K. We find three dielectrically active processes, starting from low temperatures: (i) the γ-relaxation deep into the glassy state (with an activation energy of 5.7 kcal/mol), (ii) the “fast” β-relaxation just above the calorimetric Tg, with an activation energy of 11.4 kcal/mol, and (iii) the mixed αβ-relaxation which has many similarities to a single α-process. Dynamic light scattering also identified the last two processes. The distribution of relaxation times for the αβ-relaxation exhibits a strong T dependence ranging from a Kohlraush−Williams−Watts (KWW) parameter of 0.25 at Tg to about 0.7 at Tg + 115 K. This strong T dependence, which is a common feature of poly(n-alkyl methacrylates) with long side chains, reflects t...

Hydrogen Bonds of Poly[(n-alkyl methacrylate)-co-(methacrylic acid)]’s in Dilute Solutions

Abstract The nature of the association of poly[(n-alkyl methacrylate)-co-(methacrylic acid)]’s (poly(RMA-co-MAA)’s) in dilute chloroform solutions was investigated by Fourier transform infrared (FT-IR) spectroscopy and the solution viscosity. The proportions (Pfree) of free carboxyls increased with the length of the alkyl groups in RMA’s and with the decreasing MAA composition. From the relationships between Pfree and the effective concentration (Ceff) of carboxyls attached to the polymer chain, it was shown that the major substituent effects of the alkyl groups on the hydrogen bonds in the copolymers are the extension of the polymer chain and the steric effect on the association between carboxyls and ester groups. Also, from the features of the shrinkage of the polymer chains accompanied with the intrachain association of carboxyls it was suggested that the hydrogen bonds in the copolymers are formed chiefly between neighboring sites along the chain.

Nitrogen-based copolymers as wax dispersants for paraffinic gas oils

n-Alkyl acrylates and n-alkyl methacrylates were prepared by esterification of acrylic and methacrylic acids with two linear long chain alcohol blends NAFOL 1822 and NAFOL 1822C. The four synthesized monomers were characterized and copolymerized with maleic anhydride in 1:1 molar ratio individually. The prepared copolymers were subjected to partial amidation with n-hexadecylamine. The amidated copolymers were purified, characterized, and then evaluated as wax dispersant flow improvers (WDFIs) for improving the cold flow properties of a highly paraffinic gas oil G1 through cloud point (CP), cold filter plugging point (CFPP) and pour point (PP) tests. NAFOL 1822C methacrylate-n-hexadecylamine maleamic acid copolymer has achieved the highest CFPP and PP depression. Consequently, NAFOL 1822C methacrylate monomer was selected for further copolymerization with maleic anhydride in a molar ratio 1:4, respectively. The prepared copolymers were then submitted to partial and complete amidation with n-hexadecylamine, ditallowamine (ARMEEN 2HT), tetraethylenepentamine (TEPA) and morpholine successively. In addition, combined esterification and amidation of the copolymer with NAFOL 1822C and morpholine, respectively, was carried out. Evaluation of the synthesized products as WDFIs in a less paraffinic gas oil G2 revealed that nitrogen and/or oxygen based functional groups of the copolymers are controlling parameters judging their dispersing effect and that NAFOL 1822C methacrylate-n-morpholine amide of NAFOL 1822C maleate copolymer has attained the optimum performance. Results also showed that no correlation is found between gas oil flowability improvements (ΔPP) and filterability amelioration (ΔCFPP). Stability of performance of the prepared additives as wax dispersants lasted for four weeks while for two weeks only as flow improvers.

Role and relevance of polarity and solubility of vinyl monomers in graft polymerization onto starch

The relevance of polarity and solubility of vinyl monomers in graft polymerization onto starch was re-examined employing a wide spectrum of vinyl monomers. In the light of earlier assumptions that higher the polarity and solubility of the vinyl monomer, higher will be the grafting, the present investigation, in stark contrast, has brought forwad the fact that the graft polymerization is independent of the polarity and solubility of the vinyl monomer. And that no interrelation, whatsoever, exists between the grafting ability of a vinyl monomer and its polarity and solubility. Ceric ammonium nitrate was used as the graft initiator. Percentage grafting, grafting efficiency and homopolymer contents were the parameters that were used for monitoring the graft polymerizations. Infrared and acid hydrolysis techniques were used for the confirmation of graft copolymer formation. Interestingly, in the case of n-alkyl acrylates and methacrylates, as the length of the n-alkyl group increases, the grafting percentage and homopolymer content decrease which was attributed to their increase in steric hindrance. As a minor part, an overall review of the various monomers for their ability to graft polymerize and homopolymerize was done.

Characteristic length of the glass transition

The definition of molecular cooperativity is discussed. The characteristic length of the glass transition describes the size of this cooperativity. Differential scanning calorimetry (DSC) and heat capacity spectroscopy (HCS) results of a series of poly(n-alkyl methacrylates) (alkyl = methyl, ethyl, propyl, butyl, pentyl, hexyl, and octyl) and a series of statistical copolymers poly(n-butylmethacrylate-stat-styrene) are discussed in terms of molecular cooperativity in the αβ splitting region, where a high-frequency dispersion zone a splits off into the main transition zone α and a Goldstein Johari process β at lower frequencies. The characteristic length tends to small values of order one monomer diameter in the splitting region for scenarios with an α relaxation onset. The statements about the size scale of cooperativity are conditional upon certain assumptions leading to the equation used for calculation of this size from HCS and DSC data. The step height of heat capacity (Δcp) and, with less certainty, the square root of the cooperativity volume or number (V1/2α or 1/2α) are proportional to the temperature distance from the cooperativity onset, T = Tons. © 1996 John Wiley & Sons, Inc.

Dependence of the friction process on the molecular structure and architecture of thin polymer films

The frictional properties of a homologous series of poly(n-alkyl methacrylates) (PnAMA) and a series of poly(methyl methacrylate) (PMMA) films, cast from a variety of solvents, are characterized. The choice of polymer film was driven by the consideration of the possible mechanisms for the accommodation of a macroscopically applied shear stress by molecular entities. Two possible mechanisms are proposed: (i) the relative flexibility of the polymer backbone chain. For this purpose the PnAMAs have been chosen. By varying the length of the substituent chain, the relative molecular freedom around the backbone chain is altered. These molecular differences are sensed in the frictional properties at the macroscopic level, and (ii) the molecular organization is also proposed to be a factor in determining the friction response of a particular polymer film. For this purpose, the frictional properties of PMMA films cast from different solvents are investigated. There is observed to be a strong influence of the molecular organization on the frictional properties of the solvent cast PMMA films. The molecular probe employed to characterize the molecular environment is vibrational spectroscopy. Conformationally sensitive vibrational modes are used to determine the relative flexibility of the backbone chain and the organization of the chain network.

Self-association versus interassociation in hydrogen bonded polymer blends: 2. Comparison of theoretical and experimental miscibility windows for poly(2,6-dialkyl-4-vinyl phenol) blends

Self-association and interassociation equilibrium constants determined from i.r. studies of miscible poly(2,6-dimethyl-4-vinyl phenol) (PDMVPh) and poly(2,6-diisopropyl-4-vinyl phenol) (PDIPVPh) blends with poly(n-butyl methacrylate) and an ethylene- co-vinyl acetate (EVA) copolymer are used to calculate theoretical miscibility windows for the homologous series of poly(n-alkyl methacrylate)s and the entire copolymer composition range of EVA copolymers. Miscibility gaps are predicted to increase significantly for analogous blend systems in the series PDIPVPh > PDMVPh > poly(4-vinyl phenol). One factor contributing to this trend is the steric hindrance of the 2,6-dialkyl substituents, which serve to reduce the relative strength of self-association versus interassociation. Experimental i.r. studies of these blend systems corroborate the overall shape and size of the single phase region of the predicted miscibility windows.

Effect of branched alkyl groups on physical properties in poly(ethylene-co-branched alkyl methacrylate)s

Poly(ethylene-co-5.4 mol% n-alkyl/branched alkyl methacrylate)s (PEM) were prepared by a dehydrogenchloride reaction of poly(ethylene-co-5.4 mol% alkyl methacrylic chloride) with the corresponding alkyl alcohol to investigate effect of branching structure and length of alkyl ester on a few physical properties of PEM [glass transition temperature (Tg), degree of crystallinity in polyethylene region (Xc) and dielectric molecular motion], where the alkyl groups used here are n-propyl, n-butyl, n-hexyl, n-decyl, 2-ethylhexyl, 3,5,5-trimethylhexyl and 2-(1′,3′,3′-trimethylbutyl)-5,7,7-trimethyloctyl. In the n-alkyl methacrylate copolymers, Tg and Xc were almost unchanged with the presence of alkyl ester, but Tg increased and Xc decreased in the highly branched alkyl methacrylate copolymers even at the low methacrylate content of 5.4 mol%.

Influence of Cooperative α Dynamics on Local β Relaxation during the Development of the Dynamic Glass Transition in Poly(n-alkyl methacrylate)s

The development of the dynamic glass transition in poly(n-alkyl methacrylate)s is investigated with broad-band dielectric spectroscopy in the frequency range from 10-4 to 109 Hz. The experimental data were analyzed by adjustment with one or a sum of two Havriliak Negami functions. Upon decreasing the temperature, the high-temperature relaxation (a) changes into the local β relaxation (Johari Goldstein mode), and the cooperative α relaxation sets in close to this aβ transition. For poly(n-butyl methacrylate) a separate onset (zero intensity) of the α process and a parallel course of both traces in the Arrhenius diagram were observed. The activation energy of the β process does not change in spite of the parallel development of the α process. On the other hand, for poly(ethyl methacrylate) the α onset is close to a bend in the local process, i.e., the activation energy of the latter changes after the α onset. In both materials the intensity of the α process linearly increases with falling temperatures but with different intensity. Several scenarios for the αβ-splitting region are suggested.

Functional Group Accessibility in Hydrogen Bonded Polymer Blends

Accessibility of functional groups is an important concept in the mixing of polymers and involves factors such as chain connectivity, steric shielding, etc., all of which tend to limit the number of interchain contacts formed. Infrared spectroscopy is well suited to study functional group accessibility in carefully selected miscible hydrogen bonded polymer blend systems, because the fraction of interchain hydrogen bonded groups can be measured quantitatively. Such measurements have been made on blends consisting of a wide range of carbonyl containing (co)polymers with a 2,3-dimethylbutadiene-stat-4-vinylphenol containing 24 wt % 4-vinylphenol. Evidence has been obtained for decreasing accessibility of the carbonyl groups of the poly(n-alkyl methacrylate)s due to steric shielding from bulky side groups. Conversely, when these groups are spaced further apart in an ethylene-stat-vinyl acetate or ethylene-stat-methyl methacrylate copolymer chain, they become much more accessible. The effect of functional grou...

Fine Structure of the Main Transition in Amorphous Polymers: Entanglement Spacing and Characteristic Length of the Glass Transition. Discussion of Examples

The main transition of amorphous polymers is analyzed with respect to a fine structure by means of new experimental dynamic shear, dielectric, and heat capacity data for the following polymers: poly(n-alkyl methacrylate)s with alkyl = methyl, ethyl, propyl, butyl, and hexyl, polystyrene, poly(vinyl acetate), a series of weakly vulcanized natural rubbers, a series of butyl rubbers with different carbon black content, polyisobutylene, and bromobutyl rubber. The components of the fine structure are assumed to be a proper glass transition at short times, followed by a confined flow zone, and, at large times, a hindering zone caused by entanglements at large times. Two lengths are assumed to correspond to the first and third components, respectively, the characteristic length to the proper glass transition and the entanglement spacing to the hindering zone. The confined flow will be described by a dispersion law (general scaling) across the main transition. The characteristic length of the glass transition fo...

Polymer−Surfactant Interactions Studied by Titration Microcalorimetry: Influence of Polymer Hydrophobicity, Electrostatic Forces, and Surfactant Aggregational State

Isothermal titration microcalorimetry has been applied to investigate the interactions between hydrophobically-modified water-soluble polymers and surfactants. The following polymers were used in this study: poly(sodium acrylate-co-n-alkyl methacrylate) (A), where n-alkyl = C9H19, C12H25, and C18H37 (percentage of n-alkyl methacrylate to total monomer content ranging from 0 to 8), and poly(acrylamide-co-n-alkyl methacrylate) (B), where n-alkyl = C12H25 (percentage of lauryl methacrylate to total monomer content ranging from 0 to 5). The surfactants were a cyclic (mono-) n-dodecyl sodium phosphate (1) (CMP), a cyclic di-n-dodecyl sodium phosphate (2) (CDP), n-dodecyltrimethylammonium bromide (3) (DTAB), and di-n-dodecyldimethylammonium bromide (4) (DDAB). The following factors were found to influence the interactions between polymers and surfactants: electrostatic forces, polymer hydrophobicity (both the length of the hydrophobic moiety and the degree of hydrophobic modification), and the aggregational s...

Relaxations in Poly(di-n-alkyl and di-isoalkyl itaconates)

A systematic study about the viscoelastic and dielectric relaxations was performed for a family ofpoli(di-n-alkyl and diisoalkyl itaconates) : poly(dimethyl itaconate) (PDMI), poly(diethyl itaconate) (PDEI), poly(di-n-propyl itaconate) (PDPI), poly(di-n-butyl itaconate) (PDBI), poly(diisopropyl itaconate) (PDIPI), and poly(diisobutyl itaconate) (PDIBI). Three dielectric relaxation processes, labeled as α, β, and γ were observed in all cases. Nevertheless, in some polymers a poor resolution of the peaks is observed and only small indications of the phenomena can be seen. In the case of PDPI and PDBI measurements at very low temperatures were performed and dielectric absorption processes are found at those temperatures. Behavior similar to that observed for dielectric relaxations is found for the mechanical one. The temperature at which the α relaxation, associated with the glass transition temperature, is present diminishes as the length of the n-alkyl side group increases. This behavior is similar to that reported for poly(n-alkyl methacrylates). β relaxation is only detected at some frequencies, and it is more easily detected in terms of E'' or e'' than in terms oftan δ. This relaxation is less pronounced than in the case of poly(n-alkyl methacrylates). An important difference between these polymers and poly-(n-alkyl methacrylates) is the existence of a new relaxation process labeled as γ relaxation between -40 and -120 °C. This relaxation is very sensitive to the dryness of the sample or to the presence of molecules of low molecular weight in the matrix.

Surface properties for poly(perfluoroalkylethyl methacrylate)/poly(n‐alkyl methacrylate)s mixtures

AbstractA poly(perfluoroalkylethyl methacrylate) and a series of poly(n‐alkyl methacrylate)s such as poly(methyl methacrylate), poly(ethyl methacrylate), and poly(n‐butyl methacrylate) were prepared and used to investigate the surface properties of polymer mixtures containing a fluorinated homopolymer and a nonfluorinated homopolymer and the effect of the side‐chain length of poly(n‐alkyl methacrylate) on the surface free energy for the polymer mixtures. Contact angles were measured for the surfaces of polymer mixtures by varying the concentration of poly(perfluoroalkylethyl methacrylate). From the contact angle data, it can be inferred that most of the poly(perfluoroalkylethyl methacrylate) added to poly(n‐alkyl methacrylate)s is located in the outermost layer of polymer‐mixture surface. Surface free energies for the outermost surfaces of polymer mixtures were calculated from the contact angle data using Owen and Wendt's equation. The decrease in the surface free energy for the polymer mixture with the poly(perfluoroalkylethyl methacrylate) addition is more pronounced as the side‐chain length of poly(n‐alkyl methacrylate) decreases. Due to the steric effect of the side chain of poly(n‐alkyl methacrylate), the arrangement of the perfluoroalkylethyl group of poly(perfluoroalkylethyl methacrylate) to the air side is considerably hindered. The ESCA analysis of atomic compositions of the surface for the polymer mixture verified that poly(perfluoroalkylethyl methacrylate) is preferentially arranged and concentrates at the polymer mixture–air interface. The results of functional group compositions obtained by ESCA showed that the functional group composition of CF3 for the outermost layer has a more important effect on the surface free energy than that of CF2 and confirmed the hindrance of the arrangement of perfluoroalkylethyl group to the air side by the side chain of poly(n‐alkyl methacrylate). © 1994 John Wiley &amp; Sons, Inc.